Alternating-current generation



Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE IBVING LANGMUIB, OFSCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, ACORPORATION F NEW YORK .ALTERNATING-'GURRENT GENERATION Originalapplication led October 29, 1913, Serial No. 797,987. Divided and thisapplication iiled April 24, 1924. Serial No. 708,820.

My present invention relates to the production of alternating currentsof any frequency desired from any suitable source of either direct oralternating current, and more particularly to the production of highfrequency currents and thel supplying of such currents to a loadcircuit.

The present application is a division of'my prior application Serial No.797,987, filed October 29, 1918.

In carrying my invention into eiect I` make use of suitable circuitarrangements used in conjunction with an electron discharge device whichmay be of the so-called audion type. In the circuit arrangements usedthe frequency of the oscillations generated is dependent upon theresonant frequency of the circuit arrangement used with the device. Ifthe currents produced are supplied to a load circuit in the customarymanner, that is, by coupling the load circuit to the circuit in whichthe alternating currents are produced then the frequency of the currentsproduced will also be dependent to a certain extent upon the constantsof the load circuit. If any of these constants vary then the frequencyof the currents produced will also vary.

This arrangement is 'unsatisfactory 1n many cases particularly where thecurrents produced are to be employed in a high frequency signalingsystem in which it is deslrable that the frequency of the currentsemployed shall remain constant.

The object of my .present invention 1s to overcome this disadvantage andprovide a system in which the frequency ofthe currents supplied to aload circuit may be maintained constant irrespective of changes 1n theconstants of the load circuit. In obtaining this object of my invention,I interpose between the oscillation producer and the load circuit arelay which may also be of the electrond1scharge or audion type andwhich has such circuit connections that there will be substantially noreaction between the load circuit and the circuits which determine thefrequency of the oscillations produced. This relay may also preferablyserve as an amplifier and thereby cause to be delivered to the loadcircuit a much greater amount of energy than that which is representedby the oscillations originally produced.

The nature of my invention will best be understood by reference to thefollowing description taken in connection with the accompanying drawingin which I have shown diagrammatically one wa in which my invention maybe carried into effect.

In the drawing l represents an electron discharge tube which comprisesan evacuated receptacle 2 in which is placed a cathode 8, an anode 4,which in some cases may be in the form of a plate, and a conducting body5, which is preferably in the form of a grid, interposed between thecathode and anode. The cathode used is preferably in the form of afilament which may be raised to incandescence by current from anyconvenient source as the battery 6. While this is the preferred methodfor causing the cathode to emit electrons, other methods may be used.The two electrodes 8 and 4 are connected by an oscillatory circuitcontaining an external source of current 7, which may be a battery asshown, or may be either a direct or alternating current generator, andan inductance 8; the circuit thus formed for convenience in descriptionI call the plate circuit. The j cathode is also connected externallywith the grid 5 through an inductance 9. The oscillatory circuit thusformed I designate the grid circuit. The two circuits are preferablycoupled together by placing the inductance 8 in inductive relation tothe inductance 9. This coupling may be a very loose one or may beomitted entirely as the capacity between the electrodes and the grid 5may electrostatically couple the two circuits together suiiiciently toproduce a current in the grid circuit whenever there is a change in thecurrent fiowing in the plate circuit. If the grid were absent, therewould be a steady flow of current in the plate circuit between theelectrodes. With the grid circuit connected, however, as soon as currentstarts to iiow in the plate circuit, a current is induced in the gridcircuit. I f the inductances 8 and 9 are wound in the same direction,when current in the plate circuit begins to build up,

then the current in the grid circuit will tend to flow in the oppositedirection and the grid will become negatively electrified. A'Ihis cutsdown the low ofcurrent in the plate circuit and as the currentdecreases, theV grid loses its negative potential and becomes positive.This allows the current to increase againin Y the plate circuit. Thesechanges may take place with great rapidity, their frequency de pendingupon the natural periods of the two circuits. The frequency of thecurrent changes may be readily varied by varying the constants of thegrid circuit and by so'doing, current of any frequency desired may beobtained in the coil 11, which should be closely coupled to the coil 8,and the current so obtained may be used for any purpose desired.

-them to a One convenient way of varying t e frequency is bythe use ofan adjustable condenser 10 in the grid circuit. I

I have also shown in the drawing a system whereby oscillations producedin the manner described may be applied for transmitting signals bywireless telegraphy. In order 'to be able to break up the oscillationsinto successive wave trains as required to roduce' signals, a key 12 maybe inserted in t e plate circuit. If the oscillations produced weresupplied directly to a load circuit such as an antenna, as for example,by including the coil 11 in the antenna circuit, then the fre- 14:,although other sources of current may be used if desired. Theoscillations produced in in the coil 11, which is connected to the gridcircuit of the second tube produce alternately positive and negativepotentials on the grid 15. When the rid potential isnegative the currentin the p ate circuit is interrupted and when the grid potential becomespositive, current 'iows through the plate circuit and the primary 16 ofa'transformer whose secondary 17 is connected directly in the Acircuitof antenna 18. The antenna is connected to earth through the condenser19in the usual manner. By this means it will be seenthat oscillations ofthe same frequency as those setup in the coil 11 but representing muchgreater energy will be impressed upon the antenna, and that thefrequency of the oscillations supplied will be independent of theantenna constants. It

willof course be understood that this method of ampliing oscillations.and .supplying oad circuit will be useful `whether 'v V.theAoscillations are produced b the systemwhich I have-disclosed or by oter methods,f1

such for example, as by 'ai highfrequency alternator.. Y Y

VWhat I claimas new and desire to secure; vby Letters Patent of.theUnited States, is: Y' 1. An oscillation'generator comprising a jresonant circuit forA determining :the fre.

quency supplied by said generator,aload`c-r1 'l Y cuit adapted-.to beenergized by'said gini-v erator and a threeelectrodeelectricdischargerepeater for transferring alternatingcurrent lv i energy from said'generatorto said loadcircuit and preventing saidload circuit from reacting on said generator.

2. An oscillatlon generator. susceptible to lreactive effects, analternating current load circuit and a three-electrode asymmetricallyconducting repeater for transferringalternating current of the generatorfrequency to said loadcircuit. f

3. An oscillation generator susceptible to.

reactive effects, an alternating current'load circuit and an audionrepeater for transfer-v A ring current of the generator frequency tosaid load circuit. p

4. An oscillation generator of the feedback type, a reactive loadcircuit, an asymmetrically conducting repeater device having threeelectrodes, means for coupling said generator to two of said electrodesand means for coupling said load circuit to one of said first mentionedelectrodes and to the third electrode.

v5. An oscillation generator of the audion type, an alternating currentload circuit and an audion repeater between said generator and said loadcircuit whereby the frequency of the current supplied by said generator1s independent of the character of said load circu1 6. An oscillationgenerator comprising a discharge'device having an input circuit and anoutput circuit reacting on said input circuit, a load circuit forcoupling sald generator to a load, and an asymmetrically 'conductingrepeater in circuit between said gen' eratorand said load for preventingsaid load from reacting on said generator.

7. In a system of distribution, an oscillation generator comprising adischarge device having an anode, a cathode and an impedance4controlling electrode and input and output limpedance.controllingelectrode connected between said-output circuit and said load circuitwhereby the load'is prevented from reacting on said generator..

8. An'electron'discharge device lhaving an input circuit and -an outputcircuit reacting upon said input circuit, 'a load circuit enerrepeatercapable of gized from said output circuit, and an as ymmetricallyconducting repeater element between said output circuit and said loadcircuit.

9. In a system of distribution, a circuit for absorbing energy, adischarge device in said circuit for amplifying said energy, an outputcircuit for said discharge device, means for transferring energy fromsaid output circuit back to said first circuit, a load circuit energizedfrom said output circuit, and an asymmetrically conducting repeaterdevice between said output circuit and said load circuit.

10. In, a system of distribution, a discharge device having an anode, acathode and an impedance controlling electrode and input and outputcircuits, means for transferring energy from said output circuit to saidinput circuit, a load circuit energized from said output circuit, and adischarge device constituting a repeater having an anode, a cathode andan impedance controlling element connected between said output circuitand said load circuit whereby the load is prevented from reacting onsaid iirst-mentioned discharge dev1ce. Y

11. A generator of sinusoidally varying waves comprising reactanceelements for determining the frequency of the waves generated, thefrequency of said generator being affected by the react-ion of otherreactance elements on said frequency determining reactance elements, areactive load circuit yconnected to said generator to be supplied withsinusoidal waves of the frequency of the waves generated by saidgenerator, in combination with means for preventing said load circuitfroml affecting the frequency of the waves supplied comprising a spacedischarge repeating from said generator to said load circuit but notcapable of repeating from said load circuit to said repeater.

12. A generator of alternating current waves the frequency of whichvaries as the impedance connected to said generator varies-other things,circuit consisting of a radio antenna to be supplied with alternatingcurrent of the freuency produced by said enerator, and means I orpreventing said load circuit from reacting on and affecting thefrequency of said generator comprising a unidirectional repeating devicecapable of repeating onl in the direction from said generator to saidlbad circuit.

being equala load be destroyed by variations in impedance of a loadconnected thereto, and a repeater having an input circuit and an outputcircuit, the input circuit being connected to said generator and theoutput circuit being connected to said load circuit, said repeater beingsuch that the impedance of the input circuit over the working range offrequencies is a substantially constant quantity independent of theelectrical condition of the output circuit or of the load circuitconnected thereto.

14. An oscillation electric discharge device having input and outputcircuits which are coupled in feedback relation and which comprisereactances that substantially determine the frequency of theoscillations produced, a reactive load circuit to which oscillations areto be supplied, and an alternating current repeater having an inputcircuit associated with said generator to receive alternating currenttherefrom, and an output circuit associated with said load circuit toimpress repeated alternating current of the frequency produced by saidgenerator thereupon, said repeater input and output circuits beingasymmetrically connected whereby the impedance of the input circuit issubstantially negligibly iniiuenced by the impedance conditions of saidoutput circuit and said load circuit is prevented from reacting uponsaid generator ."o change the characteristics of the generatedoscillations.

In witness whereof, I have hereunto set my hand this 23rd day of April,1924.

IRVING LANGMUIR.

13. Means for impressing an unvarying alternating voltage upon a loadcircuitconsisting of a radio antenna comprising an alternating currentgenerator of the type including a discharge device having a feed-backcircult and frequency determining reactance connected thereto, saidgenerator being such that the uniformity of its oscillations wouldgenerator comprising an l

